Piston-packing.



F. E. SMALL.

PISTON PACKING.

APPLIOLTIOK nun arm. n. 1914.

1,129,910. Patented Mar. 2, 1915.

.piston head;

FREDERICK E. SMALL, OF NEEDHAM, MASSACHUSETTS.

PISTON-PACKING.

Specification of Letters Patent.

Patent-ed Mar. 2, 1915.

Application filed September 11, 1914. Serial No. 861.322.

To all whom it may concern:

Be it known that I, Fnnnsniox E. SMALL,

a citizen of the United States, and resident of Needham, in the county of Norfolk and State of Massachusetts, have invented new and useful Improvements in Piston-Packing. of which the following is a specification.

This invention relates to piston aekings and while adapted to the packingo? istons generally, it is especially-designed or the packing of pistons of interna combustion en ines. In such engines in operation the cy inder is cooled while the piston is hot, and the latter therefore expands more than the cylinder and must fit loosely within the cylinder to avoid binding. In order to maintain the high compression which is nec essary, the packing mustbe tight not only between the packing and the cylinder but between the packing and the groove of the piston to prevent e-akage underneaththe piston rings.

The principal object of the resent invention is to produce anovel an improved metallic piston struction.

In the accompanying drawings which illustrate an embodiment of the invention,

Figure l is a perspectiveview of the-three rings which constitute the packing; Fig. 2 is a side elevation of the packing rings in place ona piston head; Fig. 31is a sectional view of said acking-rings-in place on the 3, illustrating another. form of the invention; and Fig. 5 is an enlarged detail view in cross section, illustrating'a slight modification of the structure shown in Fig.'4.

Referring to the drawings, *A'represents one of the two packing. rings. The ring A is divided at a single point a, but is otherwise continuous; and is resilient and normally tends to expand by its own'resihency. The

spring ring A is L-shaped in cross section and has the laterally extending flange a and longitudinally extending flange a. The end of the flange a. is adapted to bear against the walls of the cylinder, and theqend of the flan c a bears against one'of'thesidewalls of t e groove in the piston. The ring'A is also provided with the inwardly facing bevel surface a at its outer angle. 'B represents the other packing ring, divided'at a. single aching which shall accomplish these resu ts and which shall alsobe simple in construction and free from mul--. tiplicity of parts and complexity of con-'- 'the side walls of'the groove.

point I). The making ring B is also a springring ten ing to expand by its own resiliency, and is rectangular in cross section so as to fit exactly within the inner angle of the packing ring A. The position of the twor ings when assembled is best shown in Figs. 3 and 4. The spring ring C is a forcing ring or follower ring divi d at a single point 0 and normally tending to expand by its own resiliency. In the forms shown in Figs. 1, 2 and 3 said forcing rin has an outwardly facin bevel surface a, which bears against and cooperates with the bevel surface a of the packm ring.

The three rings are assemb ed in the circumferehtial groove G of the piston h'ead D in such osition that the oints of division a and b 0 the two packing rings break joint.

The ring A is rovided with a pin 7) which projects into the opening I) of the ring B to hold the two rings in broken joint relation and revent them from working into such position that the openings (1 and b will register. WVhen assembled in the groove of the piston head as shown in Figs. 2 and 3,

the natural resiliency of the packing rings A and B tends to expa d the packing into close engagement with t e inner wall of the cylinder E. The'groovefi is wider than the combined width of the packing rings A and B so that the packing rings will fit loosely in thegroove and befree to expand or contract withoutany tendency to bind between The forcing ring C, cooperating with the bevel surface a.

' of the packing ring A, by reason of its exi ig. 4 is a view similar to'Fig; j

face (1 tends maid in the expansion of the packing rings A, B,and thereby to effect a tight c osure between the peripheries of said rings and the cylinder wal E; while the other com onent of said orce tends to thrust sai packin rings bodily endwise with relation to tie piston head D and thereby to hold-the packing rings A, B, in tight engagement with one side of the groove G. Thus, the packing is maintained tight against lossof 'ressure both between the rings and the cylinder wall and underneath the rings between the rings and the piston head.

The combined width of the packing rin is substantially less'than the width of t e annular groove G. in the piston, so that s 'i It rin s to be easil inserted into their rooves by first inserting one end of the ring into the groove, bending the. ring slightly for that purpose and tipping the ring-relativelyto the axis of the piston, and then springing the rest of the ring into the groove b; following around the ring until the whole is sprung into the groove. possible by having the groove substantially wider than the rings, so that the roove will receive the rings when tipped or tilted to the axis ol the piston. In the usual form of snap packing rings, the ring exactly fits and iills the groove, with the result that the ring cannot be inserted part at a time because the groove will not receive the ring when tilted, but must be sprung all at once over the piston, and snapped into the groove all at once. This tends either to stretch and distort the ring so that it will not make a good joint, or frequently to break the ring. The removal of such snap rings is attended withevcn greater dilliculties, since there is not only the danger of distorting or breaking .the ring, but it cannot be removed at all without inserting the usual expanding strips under the. ring in the manner.familiar to engineers. With the present invention there is comparatively little distortion of the rings and no danger of breaking them; and they can be readily inserted andremovcd without the aid of implements. Another advantage of making the groove wider than the rings is that a clear and free space is rovided to admit steam behind the rings w ich aids iii setting the packing by steam pressure.

In the forms shown in Figs. 4 and 5,'the packing rings A, B, are of the same construction as already described. The spring follower ring C (Fig. 4) instead of having the cross sectional shape of the spring -ring C, is substantially circular in cross section, its rounded surface bearing against the bevel surface a of the packing ringA. The follower ring C in Fight is made of a round Coplen o! thirpatent may bc -obtained for This is rendered drawn steel wire, and is left rounded on all sides. In the form shown in Fig. 5 the t'ollower ring (J is also made of a round drawn steel wire, ground flat on the side which bears against the side wall of groove (l. An advantage of using a follower ring of the form shown in Figs. l: on 5, is that the round surface which bears against the bevel surface a accommodatesitself to any angle or form of bevel and does not require the nice fittingnecessary when a bevel follower ring of the form shown-at C is used. .lhus the rounded surface ring is cheaper-to make .and more certain and perfect inits action,

espeeially'if any irregularities are present in the bevel .form of ring. The provision of the flat bearing surface 0 (Fig. 5) possesses the further advantage that there is less likelihood of the ring wearing a groove in the side wall of the channel (1, and less likelih00d of the ring C becoming wedged be tween the ring A. and-the wall of channel G in use.

I claim In combination, a. piston having an annular groove therein, and a packing in said groove comprisinga continuous resilient packing ring L-shapcd in cross section and divided at a single point, said ring having a beveled surface at 1ts outer angle, a second continuous resilient packing ring divided at a single point, filling the inner angle of said L-shaped ring and arranged to break joint therewith, the combined width of said rings being substantially less than the width of said groove, whereby a-"clearance is provided between the side of said packing rings and the side of said groove, and aspring follower ringengaging the beveled surface of said L-shapedpacking ring and one wall of .said groove, and adapted to urge said two packing rings in both a radial direction and 'an endwise direction on the piston against the opposite wall of said groove.

Signed by me at Boston, Massachusetts, this 3rd day of Se tember 1914. I

FRE ERICK E. SMALL.

. Witnesses: y

RICHARD W. HALL, 'Rommr CUsimaN.

five cents each, by addressing the "Uommiasloner of Patents.

Wnhlngton, D. 0. 

